Field of the Invention
The present invention relates to a method of recovering 1,3-propanediol PDO) from fermentation broth.
1. Background Art
1,3-propanediol (PDO) is a precursor of polytrimethylene terephthalate which is a raw material for making polymeric fiber. Conventionally, ethylene oxide is used to chemically produce PDO (Chopey, N., Chemical Engineering106(5):56-62 (1999)). Ethylene oxide is first converted to 3-hydroxyl-opionaldehyde (3HPA) in presence of a cobalt-based catalyst. Then 3HPA is catalytically hydrogenated to produce PDO. Distillation is used to separate PDO from impurities.
Other chemical routes to 1,3-propanediol are known. For example, 1,3-propanediol can also be prepared by the catalytic solution phase hydration of acrolein followed by reduction; or from hydrocarbons such as glycerol, reacted in the presence of carbon monoxide and hydrogen over periodic table group VIII catalysts. Although it is possible to generate 1,3-propanediol by these chemical methods, they are expensive and generate waste streams containing environmental pollutants. See, for example, U.S. Pat. Nos. 5,015,789; 5,689,016; 5,723,389; 5,731,478; 5,821,092 and 5,841,003.
PDO can also be produced biochemically by fermentation (Chopey, N., Chemical Engineering 106(5):56-62 (1999)). In these methods, substrates such as glycerol and glucose, for example, are converted to PDO by microorganisms. See, for example, U.S. Pat. Nos. 4,962,027; 5,164,309; 5,254,467 and 5,821,092. The advantage of the fermentative route is lower raw material cost. Accordingly, there is considerable interest in making PDO fermentatively.
Methods for the purification of 1,3-propanediol are known in the art. These methods, however, use extraction with an organic solvent and distillation. See U.S. Pat. Nos. 5,254,467 and 5,356,812. A particularly good organic solvent for this process is cyclohexane (U.S. Pat. No. 5,008,473). Distillation is usually an energy intensive step. Solvent extraction uses organic solvents which can cause environmental problems. Therefore, there is a need for an effective separation method to recover PDO from fermentation broth.
Simulated moving bed (SMB) technology is a convenient and efficient method of chromatographic separation of fermentation broth (U.S. Pat. No. 2,985,589).
It is an object of the invention to provide a method of recovering 1,3-propanediol from a liquid composition comprising a) contacting said liquid composition comprising said 1,3-propanediol with a cationic resin; b) adding solvent and eluting fractions from said resin; and c) recovering said 1,3-propanediol from a product fraction comprised of fractions of part b) comprising detectable ,3-propanediol; wherein said method of recovering lacks a distillation step.
It is a further object of the present invention to utilize simulated moving bed technology to effect the recovery of 1,3-propanediol from a liquid composition. Further object and advantages of the present invention will be clear from the description that follows.